Toward DDT-Free Malaria Control
Burton, Adrian, Environmental Health Perspectives
Good judgment comes from experience, and a lot of that comes from bad judgment.
Will Rogers (1879-1935)
An increased international effort to reduce the incidence of malaria around the globe while reducing reliance on DDT was announced 6 May 2009 at the fourth meeting of the Conference to the Parties to the Stockholm Convention on Persistent Organic Pollutants (POPs). With funding of more than US$70 million, the United Nations Environment Programme and the World Health Organization have launched 10 projects to help test integrated vector management (IVM) systems for malaria control. These systems could provide sustainable, effective, and cost-effective alternatives to reliance on DDT. The aim is to reduce DDT application by 30% over current usage by 2014, with a complete phase out by the early 2020s. About half the funding for the projects comes from the Global Environment Facility (GEF), the financial arm of the Stockholm Convention, which provides financial and technical assistance to help countries phase out and reduce releases of POPs.
DDT is banned for all uses in all countries that are signatories to the Stockholm Convention except for spraying inside buildings in developing countries where malaria is a problem. This practice, known as indoor residual spraying (IRS), is increasingly relied upon in Africa and Asia, given the resurgence in malaria in recent decades. Reports also exist that, on occasions, some developing countries contravene the Stockholm Convention and spray DDT on a larger scale. However, growing evidence of mosquito resistance to DDT as well as adverse human health effects has prompted a search for alternatives.
"There is a large and growing body of literature on the potential human health effects of DDT," says Brenda Eskenazi, a professor of epidemiology and maternal and child health at the University of California, Berkeley. "Evidence suggests that exposure to DDT and its breakdown product DDE at levels substantially lower than that experienced in communities that use IRS may be associated with breast cancer, diabetes, spontaneous abortions, decreased semen quality, and impaired child neurodevelopment."
Great care is taken and safeguards followed in the new projects--which involve 40 countries across Africa, the Eastern Mediterranean, and Central Asia--to ensure that malaria incidence does not increase in the project areas, says Laurent Granier, coordinator of the Chemicals Cluster for the GEF. The new projects follow a successful pilot project in Mexico and Central America that achieved an overall 63% reduction in the incidence of malaria and a more than 86% reduction in the most severe form of malaria, that caused by Plasmodium falciparum. This success has rekindled hopes that an end to DDT reliance is possible.
IVM achieves such reductions with strategies such as using insecticide-treated bed nets, draining standing water from ditches, adding fish that feed on mosquito larvae to water supplies, clearing vegetation cover for adult insects, and improving diagnostic and treatment capacity to reduce the reservoir of blood parasites in the human population. …